Land vehicles – Wheeled – Occupant propelled type
Reexamination Certificate
1998-07-30
2001-07-17
Boehler, Anne Marie (Department: 3618)
Land vehicles
Wheeled
Occupant propelled type
C188S026000
Reexamination Certificate
active
06260869
ABSTRACT:
TECHNICAL FIELD OF THE INVENTION
The present invention relates generally to motorcycles and in particular the present invention relates to a motorcycle front suspension system.
BACKGROUND OF THE INVENTION
Excelsior-Henderson Motorcycle Co. began producing motorcycles in the early 1900's. The early generation motorcycles included a front suspension system which incorporated a leading-link system. The leading-link system was based on a cantilever design where the axle of the front wheel was positioned in front of both rigid forks and spring forks. Although the system performed exceptionally well for motorcycles of that era, modern motorcycles are substantially larger and more powerful than their predecessors. As such, there is a need for an improved suspension and braking system compatible with today's motorcycle designs.
The performance of a motorcycle front suspension system is critical to both safety and operator comfort. With regard to safety, the front suspension system plays an important role in braking and steering. The front suspension system also contributes to rider comfort by absorbing shocks experienced during operation, and stabilizes the motorcycle during braking.
During braking operations, forward momentum of the motorcycle and its rider compress the front suspension. By compressing the front suspension during braking, the motorcycle rider experiences a diving sensation. To counteract this front end compression, the front suspension shock absorbing system can be adjusted to provide more compression damping, thereby resisting compression during braking. By increasing the stiffness of the front suspension, however, rider comfort is sacrificed during normal operation.
Different motorcycle front suspension systems have been described which attempt to reduce the amount of front end dive which is experienced during braking. For example, U.S. Pat. No. 4,775,163 issued Oct. 4, 1988 describes a motorcycle front suspension system which includes a leading link system having a rigid fork, a spring fork, and a rocker member. The rigid fork is attached to one end of the rocker member, and a front wheel axle is attached to an opposite end of the rocker member. The spring fork is attached to the rocker member at an intermediate location between the rigid fork and the spring fork. The suspension system also includes a brake caliper located in front of the spring fork and attached to both the front wheel axle and to the rigid fork through a link member. The patent describes the configuration as approximating a parallelogram having as its sides a segment of rigid fork, the rocker member, the brake caliper, and the link. It is asserted that when the front brake is applied and momentum drives the spring fork downward, the link induces a force up the rigid fork to increase the resistance of the suspension to retard “diving” of the motorcycle's front end.
U.S. Pat. No. 4,184,695 issued Jan. 22, 1980 also describes a motorcycle front fork assembly which includes a leading link suspension having a rigid fork, a spring suspension device and a link. Again, the rigid fork is attached to one end of the link and a front wheel axis is attached to an opposite end of the link. The spring suspension device is attached part way along the link between the rigid fork and the front wheel axis. A brake caliper is positioned in front of the spring suspension device and is attached to the rigid fork using a torque arm. The rigid fork, link, brake caliper and torque arm form a parallelogram. During braking, a force is exerted downward on the front wheel thereby reducing front end dive. The suspension systems described in the U.S. Pat. Nos. 4,184,695 and 4,775,163 place high stresses on the linkage components by locating the front wheel axis in front of both the rigid and spring forks. Further, these systems do not provide anti-dive characteristics through full suspension travel. That is, the suspension systems behave differently when the brakes are applied at different times during travel of the suspension.
For the reasons stated above, and for other reasons stated below which will become apparent to those skilled in the art upon reading and understanding the present specification, there is a need in the art for a smoother suspension system which reduced component stress while reducing suspension compression due to braking operations.
SUMMARY OF THE INVENTION
The above mentioned problems with suspension systems and other problems are addressed by the present invention and will be understood by reading and studying the following specification. A front suspension system is described which reduces front end dive during braking operation.
In particular, the present invention describes a motorcycle comprising a frame, a steering head pivotally attached to the frame, a rigid fork downwardly extending from the steering head, and a compression fork downwardly extending from the steering head. A rocker arm is provided which has a first end pivotally connected to the rigid fork and an opposite end pivotally connected to the compression fork. A front wheel is rotatably mounted to the rocker arm such that an axis of the wheel is located along the rocker arm between the first and second ends.
In another embodiment, a motorcycle front suspension system comprises a rigid fork downwardly extending from the steering head, a compression fork downwardly extending from the steering head, and a rocker arm having a first end pivotally connected to the rigid fork and an opposite end pivotally connected to the compression fork. A front wheel is rotatably mounted to the rocker arm such that an axis of the wheel is located along the rocker arm between the first and second ends. A brake is located between the rigid fork and the compression fork. The brake is coupled to the axis of the front wheel with a first support member and is coupled to the rigid fork with a second support member, such that a portion of the rigid fork, the rocker arm, and the first and second support members form an irregular quadrilateral during vertical movement of the front wheel. A centerline of the second support member and a centerline of the rocker arm intersect behind the front wheel axis.
A method of reducing front end dive in a motorcycle having a rigid fork and a compression fork is described. The method comprises providing a front brake coupled to a front wheel axis and the rigid fork, and providing an upward feedback force to the rigid fork from the front brake during braking operations to compensate for a weight transfer to a front end of the motorcycle during a complete travel range of the compression fork.
REFERENCES:
patent: 940245 (1909-11-01), Gates
patent: 1101614 (1914-06-01), Bramham
patent: 2969992 (1961-01-01), Hahn
patent: 4184695 (1980-01-01), Roe et al.
patent: 4211454 (1980-07-01), Mitchell et al.
patent: 4421337 (1983-12-01), Pratt
patent: 4775163 (1988-10-01), McGowan et al.
patent: 4776609 (1988-10-01), Pan et al.
patent: 5186274 (1993-02-01), Hegman
Hanlon Daniel L.
Hanlon David P.
Holroyd James A.
Boehler Anne Marie
Excelsior-Henderson Motorcyle Co.
Fogg Slifer & Polglaze, P.A.
Slifer Russell D.
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